OT:Perl on Windows

[Alex Beamish]

On Fri, 11 Mar 2005 12:19:19 -0500, William O'Higgins
<william.ohiggins-H217xnMUJC0sA/PxXw9srA at public.gmane.org> wrote:
> On Fri, Mar 11, 2005 at 11:42:52AM -0500, Alex Beamish wrote:
> >However, your comment that 'your program' (whatever that is) cannot
> >read the file, nor is it able to create an output file, suggests
> >something is not right. Can you explain?
> 
> I'll try.  Here's the example program:
> 
> #/usr/bin/perl -w
> 
> $input = $ARGV[0];
> $output = 'test.txt';
> 
> open(TXT, "$input") or die "Cannot open $input for some reason, perhaps:
> $!\n"
> 
> if (-e $output) {
>    print "$output already exists, try a different name.\n";
>    } else {
>    open(OUT, ">$output") or die "Cannot open this file: $!\n";
> }
> 
> print OUT "test";
> 
> while (<TXT>) {
>         $data .= $_;
> }
> 
> print $data;
> 
> print OUT $data;
> 
> I get this error on run:
> 
> syntax error ... near ") {"
> 
> *and* test.txt doesn't get created, but there are no complaints.
> Something is wrong, but I'm just not sure what.  Any suggestions?

Well, a couple. ;)

First of all, I highly recommend you purchase a good book about
learning Perl. O'Reilly has several excellent books, and one of them
is called Learning Perl. It'll give you a good basic understanding of
the language.

Second, I can recommend Perl Monks (perlmonks.org) as a great on-line
community. Fools are not always suffered gladly, so concentrate on
lots of reading and very little writing when you first arrive.

Third, always use 'strict' -- it will catch your errors at compile
time rather than at run time.

Fourth, when you report an error, a line number is always handy. It
turns out that you forgot a semi-colon at the end of one of your
lines. The fixed up program is as follows:

------------------------------
#/usr/bin/perl -w

#  Usage: test.pl [input_file]

use strict;

my $input = shift;
my $output = 'test.txt';
my $data;

#  Check that the output file exists, and exit if it does.

if (-e $output) {
  print "$output already exists, try a different name.\n";
  exit;
} else {
  open(OUT, ">$output") or die "Cannot open this file: $!\n";
}

#  Write out a line of test output to the output file.

print OUT "test\n";

#  Open the input file.

open(TXT, "$input") or 
  die "Cannot open $input for some reason, perhaps:$!";

#  Read the entire input file into a scalar.

while (<TXT>) {
       $data .= $_;
}

#  Dump the entire file (contained in the scalar) to STDOUT

print $data;

#  Same thing, but dump file to the output file.

print OUT $data;

close ( OUT ) or
  die "Unable to close output file: $!";
------------------------------

and when I run it ..

------------------------------
[alex at rand dev]$ perl -w tlug-mar11.pl wtime.sh
#!/bin/sh

while wtime.pl; do
  sleep 120
done

[alex at rand dev]$ cat test.txt
test
#!/bin/sh

while wtime.pl; do
  sleep 120
done
------------------------------

It works fine.

I won't go over all of the improvements .. just compare your code to
mine and see where I've made some changes.

Alex
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